1. Field of the Invention
The present invention relates to a CT data processing apparatus and a CT data processing method for separating a region indicative of subcutaneous fat from a region indicative of visceral fat on CT (Computer Tomography) data of an examinee.
2. Description of the Related Art
Conventionally, a technique is known, in which tomographic data of a small animal is imaged by X-ray CT tomography and the amount and position of fat are analyzed based on the tomographic data. Fat includes subcutaneous fat and visceral fat and there is sometimes a case where they need to be distinguished from each other for evaluation. However, the CT values of both the fats are −250 to −50 and therefore it is not possible to distinguish between the respective fat regions using the CT values.
In order to deal with this problem, various methods of separating fat regions have been developed. Among them, there is a method in which a person who measures draws a separation line based on his/her impression of a CT image. Since it requires the person who measures to draw a separation line, many man-hours and much time are necessary and not efficient, although an exact separation line can be drawn. On the other hand, a method is known, in which a separation line is drawn automatically by processing (for example, refer to Japanese Unexamined Patent Publication No. 2003-339694).
In the tomographic image processing apparatus stated in Japanese Unexamined Patent Publication No. 2003-339694, the muscular layer between subcutaneous fat and visceral fat is focused on and then the skin layer is removed by image processing, the region of muscular layer is extended to separate between the respective fats and the subcutaneous fat is extended inwardly by the amount of the extended muscular layer.
However, in such an image processing apparatus as described above, the fat region itself to be evaluated is removed or extended. Although its effect is canceled out by extending the fat region afterward by the amount of removed region, however, there is the possibility that the result to be obtained may be incorrect because the fat region deforms into one different from the original one. In addition, if separation is not accurate, it will be required to modify the separation, and after all, the working efficiency is decreased.